A surface plasmon resonance device (hereafter referred to as an SPR device) has been used in which a phenomenon for obtaining a high optical output by a resonance of an electron and a light in a minute region of a nanometer level or the like (a surface plasmon resonance (SPR: Surface Plasmon Resonance) phenomenon) is put to practical use and an extremely fine analyte in a biological body is detected for instance.
As shown in FIG. 12, the SPR device 100 is provided with a sensor structure 110 in which a metallic thin film 104 is formed on the top surface of a dielectric member 102 and a ligand containing layer 108 that includes a ligand immobilized region 106 is formed on the metallic thin film 104.
Moreover, the SPR device 100 is provided with a light source 114 that is configured to apply an excitation light 112 toward the metallic thin film 104 and a light receiving means 118 that is configured to receive a reflected light 116 that has been applied from the light source 114 and that has been reflected on the metallic thin film 104 on the side of the dielectric member 102 of the sensor structure 110.
In the case in which the SPR device 100 is used, a ligand is affixed to the ligand immobilized region 106 formed on the metallic thin film 104, and a sample solution that includes a specific analyte is supplied to that.
Moreover in this state, the excitation light 112 is applied at a resonance angle θ1 from the lower side of the dielectric member 102 to the metallic thin film 104, and the reflected light 116 that has been reflected on the metallic thin film 104 is received by the light receiving means 118.
In the case in which the excitation light 112 is applied at a resonance angle θ1 toward the metallic thin film 104, a crude density wave (a surface plasmon) is generated on the metallic thin film 104, and a coupling of the excitation light 112 and an electronic vibration in the metallic thin film 104 occurs, thereby causing a light amount of the reflected light 116 to be reduced.
For this phenomenon, a resonance angle θ1 is varied depending on an existence of an analyte. Consequently, by previously researching a resonance angle θ1 in the case in which a sample solution that does not include an analyte is supplied to the ligand immobilized region 106, it can be judged that a specific analyte is included in the case in which a resonance angle θ1 is different from a resonance angle θ1 at that time.
By this configuration, it can be judged whether or not a predetermined analyte is included in a sample solution.
On the other hand, a surface plasmon field enhanced fluorescence spectroscopic measurement device (hereafter referred to as an SPFS device) has also been developed in which the analyte detection can be carried out with a higher degree of accuracy as compared with the SPR device 100 based on a principle of a surface plasmon excitation enhanced fluorescence spectroscopy (SPFS: Surface Plasmon-field enhanced Fluorescence Spectroscopy) for putting a surface plasmon resonance (SPR) phenomenon to practical use.
As shown in FIG. 13, the SPFS device 200 is provided with a sensor structure 210 in which a metallic thin film 204 is formed on the top surface of a dielectric member 202 and a ligand containing layer 208 that includes a ligand immobilized region 206 is formed on the metallic thin film 204.
Moreover, the SPFS device 200 is provided with alight source 214 that is configured to apply an excitation light 212 toward the metallic thin film 204 and a light receiving means 218 that is configured to receive a reflected light 216 that has been applied from the light source 214 and that has been reflected on the metallic thin film 204 on the side of the dielectric member 202 of the sensor structure 210.
On the other hand, the SPFS device 200 is provided with a light detection means 222 that is configured to receive a fluorescence 220 that is emitted from a fluorescence substance that has labeled an analyte that has been captured by the ligand immobilized region 206 on the side of the ligand containing layer 208 of the sensor structure 210.
A light collection member 224 that is configured to collect the fluorescence 220 in an efficient manner and a wavelength selection function member 226 that is configured to remove a light that is included in other than the fluorescence 220 and that is configured to select the required fluorescence 220 only are formed between the ligand containing layer 208 and the light detection means 222.
In the case in which the SPFS device 200 is used, a ligand is affixed to the ligand immobilized region 206 formed on the metallic thin film 204, and an analyte that has been labeled by a fluorescence substance is captured by the ligand.
Moreover in this state, the excitation light 212 is applied from the light source 214 into the dielectric member 202, and the excitation light 212 is incident to the metallic thin film 204 at a resonance angle θ2, whereby a crude density wave (a surface plasmon) is generated on the metallic thin film 204.
In the case in which a crude density wave (a surface plasmon) is generated on the metallic thin film 204, a coupling of the excitation light 212 and an electronic vibration in the metallic thin film 204 occurs, thereby causing a light amount of the reflected light 216 to be reduced. Consequently, by finding out a point in which a signal is varied (a light amount is reduced) for the reflected light 216 that is received by the light receiving means 218, a resonance angle θ2 by which a crude density wave (a surface plasmon) is generated can be obtained.
Based on the phenomenon that generates the crude density wave (a surface plasmon), a fluorescence substance of the ligand immobilized region 206 on the metallic thin film 204 is excited in an efficient fashion, whereby a light amount of the fluorescence 220 that is emitted from a fluorescence substance is increased.
By receiving the increased fluorescence 220 by the light detection means 222 via the light collection member 224 and the wavelength selection function member 226, an analyte of an infinitesimal quantity and/or an extremely low concentration can be detected.
In recent years, for the SPR device 100 and the SPFS device 200, an engineering development has been actively carried out for a further accuracy improvement.
By the way, as a method for supplying a sample solution to the ligand immobilized region 106 of the SPR device 100 and the ligand immobilized region 206 of the SPFS device 200, there can be known a supply method for supplying a solution by using a flow passage for instance.
The sensor structure 300 as shown in FIG. 14 is provided with a ligand immobilized region 306 on the metallic thin film 304 on the way of a horizontal type flow passage 308. In the case in which a sample solution 310 that includes a specific substance (an analyte) in the horizontal type flow passage 308 is sent after a ligand is affixed to the ligand immobilized region 306 in the horizontal type flow passage 308, the analyte is captured by the ligand immobilized region 306. A symbol 302 in the figure represents a dielectric member.
The sensor structure 300 that is provided with such the horizontal type flow passage 308 is designed to generate a reaction of a specific substance at any point of the ligand immobilized region 306 by circulating a sample solution 310 by using a unidirectional solution sending pump or by sending the solution in a reciprocating manner by using a reciprocated solution sending pump.
On the other hand, as another method for supplying a sample solution to the ligand immobilized region 106 of the SPR device 100, there can be known a supply method for storing a sample solution for instance.
For the sensor structure 400 that is disclosed in the Patent Literature 1, a well member 408 that is provided with a plurality of through holes 410 is formed on a ligand immobilized region 406 on a metallic thin film 404 as shown in FIG. 15, and a sample solution 412 is supplied and stored in each of the through holes 410. By this configuration, an analyte is captured by the ligand immobilized region 406 in the through hole 410.
For this method, it is not necessary that a solution sending pump is prepared like a method in which a solution sending is carried out by using a flow passage. Consequently, this method has the advantage of being able to simplify a structure as compared with the case in which a flow passage is used.